1. Field of the Invention
The present invention is generally concerned with laser ophthalmological surgical devices of the type disclosed in European Patent Publication No. 0,007,256 published Jan. 23, 1980 and in U.S. patent application Ser. No. 429,962 filed Sept. 30, 1982 now U.S. Pat. No. 4,517,980, issued May 21, 1985.
2. Description of the Prior Art
Broadly speaking, an ophthalmological surgical device of this kind comprises a laser unit adapted to emit at least one laser beam and an operating unit adapted to focus said laser beam on an aiming point.
In practice, the laser unit preferably comprises two lasers, a main operating laser of sufficiently high power for its beam to operate not by virtue of heat transfer but rather by optical breakdown, a blocked mode YAG laser emitting in the infra-red band being satisfactory for this, and an auxiliary aiming laser producing a visible beam so as to visually indicate the aiming point to the operator, in the form of a red spot of very diameter, for example.
Conjointly, the operating unit usually comprises a slit lamp.
As is known, a slit lamp of this kind generally comprises, on a common support chassis, a microscope adapted to enable the operator to observe the aiming point to be treated, and a slit projector, that is to say a luminous optical device adapted to form a luminous slit in the focusing plane of said microscope, to facilitate observation of the aiming point.
For purposes in particular of adaptation to the morphology of the patient to be treated, the support chassis of a slit lamp of this kind is generally adjustable in position on a base, in practice a plane base, under the control of control means accessible to the operator. The chassis is adjustable parallel to the base, in two orthogonal directions in the plane thereof, one corresponding to a depth adjustment along the aiming axis and the other to a lateral adjustment, perpendicular to the aiming axis. It is also adjustable in height, perpendicularly to said base.
Conventionally, these control means comprise a swinging arm providing depth adjustment when moved forwards and backwards and lateral adjustment when moved to the right and to the left, and also a knob providing the height adjustment, disposed at the base of and around the swinging arm.
It will be apparent that simultaneous manipulation of a swinging arm of this kind and a knob of this kind is difficult.
Also, the operating unit comprises a focusing lens for focusing the laser beam or beams emitted by the laser unit onto the aiming point. For example, and as described in the aforementioned U.S. patent application Ser. No. 429,962, this lens may constitute the exit lens of said laser unit.
In practice, the operating unit further comprises, on the exit side of its focusing lens, a mirror adapted to reflect the laser beam or beams emitted by the laser unit onto the aiming point, the beams being usually incident along the aiming axis whereas the laser unit is disposed to the side of this axis.
Conventionally, this focusing lens and this mirror are fixed in position on the chassis supporting the slit lamp.
An ophthalmological surgical operation normally involves action at a plurality of separate points spaced along a determined path.
To track the aiming point of the laser beam or beams along this path, the operator has previously been required to appropriately and continuously adjust the position of the chassis supporting the slit lamp relative to its base.
As already emphasized, this adjustment of the position of the chassis supporting the slit lamp previously involved the simultaneous manipulation of a swinging arm and a knob, being particularly difficult to achieve in a secure manner in that it requires excellent coordination.
A general object of the present invention is an arrangement intended to facilitate tracking the aiming point along a path.